Chess in a Few Bytes
Linux has a good range of extremely strong chess engines such as Stockfish, Critter, Togo II, Crafty, GNU Chess, and Komodo. The chess engines featured in this article offer no match to a good chess engine, but they show how much can be achieved with a minuscule codebase.

360-FAAR (Firewall Analysis Audit and Repair) is an offline, command line, perl policy manipulation tool to filter, compare to logs, merge, translate and output firewall commands for new policies, in checkpoint dbedit or screenos commands, and its one file!

Appctl is a framework for virtually any server software. It provides a central script called "ctl" which allows you to start, stop, restart, maintain, or query the current status of an application. It is meant as a completely generic replacement for application-specific startup/stop scripts. The project also supplies generic monitoring scripts for clusters, which can dramatically decrease clustering costs.

Archive sort is a script that sorts directories into manageable 4.4GB directories for the purpose of archiving onto DVDs. It is useful if you have several tens or hundreds of GBs of data to archive. It can also be configured to sort into 700MB directories for archiving onto CDs.

AutoUpdate is a Perl script which performs a task similar to RedHat's up2date or autorpm. It can be used to automatically download and upgrade rpms from different (s)ftp or http(s) sites. Moreover, it can also be used to keep a server with a customized (RedHat) distribution plus all clients up to date.

bluelock.pl is designed to lock a display or terminal once a Bluetooth device (like a cell phone) is out of range. The script queries the RSSI (signal strength) of a Bluetooth device. Once the RSSI passes above a certain threshold a timer is started, and once the timer expires a locking program is run.

Darius Tools is a collection of miscellaneous scripts which are useful for a variety of purposes and include scripts for mass conversion of WAV files to Ogg files and Ogg files to WAV files, for converting LaTeX to PostScript and viewing the output in ggv, for creating image thumbnails, for converting from the Euro to another currency, for automated updating via FTP and for removing backups recursively.

dd_rhelp allows users to retrieve, quickly and easily, recoverable data from any device with bad sectors. It will copy it using dd_rescue in all the appropriate ways (reverse copy, setting start and stop offset accordingly to previously rescued data) to recover the maximum data possible before spending time on bad sectors. It is straightforward to use, supports ctrl-c at anytime, can resume a job (or standalone dd_rescue job) by parsing the dd_rescue logs, and displays a nice ASCII bar showing rescue progress.

a shell script, that works on top of the package management tools provided by the debian project.
The goal is to create one command that installs any package into your system, or provides information about any package, without the user having to know all the different tools there are

An archive of various shell scripts that can be especially useful to system administrators and webmasters. They need the Bash shell and standard GNU commands, both of which are installed on any Linux system. Each script has an -h flag for usage explanation. All scripts can be downloaded in a compressed tar archive.

Dotkit is a set of shell scripts, small "package" files (dotkits), and an organizing plan to help you set up, modify, maintain, and understand a working Unix environment, for one person or for an entire site.

dpkg-du is a script to produce a dump of the installed size of Debian packages in du format. This is to enable ease of reuse with pre-existing scripts administrators may have to deal with 'du' format lists.

emv is a tool for mass-renaming files with a text editor. It can perform two pass renaming, link creation, file list splitting, and link target editing. emv logs its actions as shell-script-style mv commands in case you want to undo them.

Frams' Shell Tools is a big collection of various (mostly Perl) scripts to make Unix everyday life at the command line interface more comfortable. They have grown in the author's last 20 years as a Unix user, programmer, and administrator. Some examples are: clp (Command Line Perl: a Perl "shell"), fpg (Frams' Perl grep: a grep with full Perl support), zz (generic clipboard), and nvt (Network Virtual Terminal: a better telnet for scripting).

The Fault-Tolerant Shell (ftsh) is a small language for system integration that makes failures a first class concept. Ftsh aims to combine the ease of scripting with very precise error semantics. It is especially useful in building distributed systems, where failures are common, making timeouts, retry, and alternation necessary techniques.

futil is a set of handy Linux utility scripts. These scripts can mount a remote Windows share, push your ssh public key to clients, display processes associated with a pty, tunnel a VNC or RDC session through a remote gateway via ssh, and more.

GrokEVT is a collection of scripts for reading Windows event log files on Unix. The scripts work together on one or more mounted Windows partitions to extract all information needed (registry entries, message templates, and log files) to convert the logs to a human-readable format.

inotify-tools is a set of command line utilities for the Linux inotify filesystem change notification system. It currently consists of only one utility, "inotifywait", which is used to wait for changes to a file from a shell script.

NetSQUID is a Perl script that sits inbetween Snort and IPTables. It looks at the alerts generated by Snort, then automatically creates an IPTables firewall entry to block problematic hosts (such as those infected by viruses).

po2c is a Perl script that takes a bunch of gettext (.po) language translation files from its command line arguments and dumps a C source code file containing all those messages and the necessary functions to use them without any other dependency.

Podget is a Bash script to automate the downloading Podcast audio content from RSS feeds (such as those listed at Ipodder.org), storing it in categories & folders, and automatically creating a playlist for new content.

a bash script that generates a report that describes the state of the hardware on the running machine. prtdiag does not actually acquire all of the information itself, it also relies heavily on other applications such as lspci, lm_sensors, and dmidecode to gather needed data

RDFEasy is a software distribution based on Ubuntu Linux and OpenLink Virtuoso Open Source Edition that makes it easy to load large RDF data sets (in the billion triple range) into a SPARQL compatible triple store in the AWS cloud, and then package the triple store in an easy-to-use AMI.

a set of scripts to automate the duplication of a model computer running Debian/GNU Linux, with some provisions to take into account differences in hardware (like HD size, video card) and in software configuration (partitioning

ReMove to Waste, rmw, is a bash script that functions as a Linux/Unix console recycle bin when reMoving files with rm. ReMove to Waste will move files to a Waste folder or "Trash can," and it will prepend the time and date to files when reMoving them.

screenFetch is a "Bash Screenshot Information Tool". This handy Bash script can be used to generate one of those nifty terminal theme information + ASCII distribution logos you see in everyone's screenshots nowadays.

a script that helps to search and print references in the 'See also' section included at the end of many UNIX manual pages. It can be used to locate documentation or to gain familiarity with the commands and functions available on a system

Spammergrok is a simple bash script that will take URLs on the command line, from one or more files, or extract them from one or more files containing a single email message each (via ripmime). Spammergrok will then proceed to download data from these URLs a set number of times (via wget) in an effort to waste a spammer's bandwidth.

systembackup.sh is a shell script used as a wrapper around tar archiver 'star'. The purpose of this script is to simplify systembackups. It is not intended for ad hoc backups, tar or star can be used for that without a script.

tagls is a tool that matches file names using boolean expressions made of tags and regular expressions. It handles searching in file lists with word boundaries for "tags", stemming and synonym expansion for both tags and regular expressions, and boolean expressions over lists of tags or regular expressions.

terminal_colors is a tool to display a terminal color chart for 8, 16, 88, and 256 color terminals. It provides all the functionality of the various similar scripts found around the Web with some additional bells and whistles.

urlwatch is a script intended to help you watch URLs and get notified (via email) of any changes. The change notification will include the URL that has changed and a unified diff of what has changed. The script works out of a single directory, so there is no need to install anything. State files are kept in the same folder. The script supports stripping parts of a page that are always changing through the use of a filter hook function. It is typically run as a cronjob.

a tool for automatic generation of bash scripts that sets up HTB on Linux. It uses xml configuration files. It's easy to use, It have a lot of features: multiple depths of classes, configurable leaf, u32 and fw filters

xtee (cross-tee/expanded tee) is a program for building complex pipelines. It resembles the tee command, except that instead of copying stdin to stdout, it copies a file to stdout. You can use xtee for building things like a bidirectional HTTP filter (using netcat and sed).

yeaGTD is an acronym for "yaml encoded approach to getting things done". It is a python script which extracts information from simple text files, one for each project, and then produces nicely formatted summary reports.